Abstract. Thermal infrared (IR) radiances measured near 8 microns contain information about the vertical distribution of water vapor (H 2 O), the water isotopologue HDO, and methane (CH 4 ), key gases in the water and carbon cycles. Previous versions (Version 4 or less) of the TES profile retrieval algorithm used a "spectral-window" approach to minimize uncertainty from interfering species at the expense of reduced vertical resolution and sensitivity. In this manuscript we document changes to the vertical resolution and uncertainties of the TES version 5 retrieval algorithm. In this version (Version 5), joint estimates of H 2 O, HDO, CH 4 and nitrous oxide (N 2 O) are made using radiances from almost the entire spectral region between 1100 cm −1 and 1330 cm −1 . The TES retrieval constraints are also modified in order to better use this information. The new H 2 O estimates show improved vertical resolution in the lower troposphere and boundary layer, while the new HDO/H 2 O estimates can now profile the HDO/H 2 O ratio between 925 hPa and 450 hPa in the tropics and during summertime at high latitudes. The new retrievals are now sensitive to methane in the free troposphere between 800 and 150 mb with peak sensitivity near 500 hPa; whereas in previous versions the sensitivity peaked at 200 hPa. However, the upper troposphere methane concentrations are biased high relative to the lower troposphere by approximately 4 % on average. This bias is likely related to temperature, calibration, and/or methane spectroscopy errors. This bias can be mitigated by normalizing the CH 4 estimate by the ratio of the N 2 O estimate relative to the N 2 O prior, under the assumption that the same systematic error affects both the N 2 O and CH 4 estimates. We demonstrate that applying this ratio theoretically reduces the CH 4 estimate for non-retrieved parameters that jointly affect both the N 2 O and CH 4 estimates. The relative upper troposphere to lower troposphere bias is approximately 2.8 % after this bias correction. Quality flags based upon the vertical variability of the methane and N 2 O estimates can be used to reduce this bias further. While these new CH 4 , HDO/H 2 O, and H 2 O estimates are consistent with previous TES retrievals in the altitude regions where the sensitivities overlap, future comparisons with independent profile measurement will be required to characterize the biases of these new retrievals and determine if the calculated uncertainties using the new constraints are consistent with actual uncertainties.

Abstract. The version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. The cloud top temperature, pressure, and height and effective cloud fraction are now reported at the AIRS field-of-view (FOV) resolution. Significant improvements in cloud height assignment over version 5 are shown with FOV-scale comparisons to cloud vertical structure observed by the CloudSat 94 GHz radar and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid, and unknown phase), ice cloud effective diameter (D e ), and ice cloud optical thickness (τ ) are derived using an optimal estimation methodology for AIRS FOVs, and global distributions for 2007 are presented. The largest values of τ are found in the storm tracks and near convection in the tropics, while D e is largest on the equatorial side of the midlatitude storm tracks in both hemispheres, and lowest in tropical thin cirrus and the winter polar atmosphere. Over the Maritime Continent the diurnal variability of τ is significantly larger than for the total cloud fraction, ice cloud frequency, and D e , and is anchored to the island archipelago morphology. Important differences are described between northern and southern hemispheric midlatitude cyclones using storm center composites. The infrared-based cloud retrievals of AIRS provide unique, decadal-scale and global observations of clouds over portions of the diurnal and annual cycles, and capture variability within the mesoscale and synoptic scales at all latitudes.

Thermal infrared (IR) radiances measured near 8 microns contain information about the vertical distribution of water vapor (H₂O), one of its minor isotopologues (HDO) and methane (CH₄), key gases that can be used to investigate the water and carbon cycles. Here, we show improvements in vertical resolution and reduction in uncertainties for estimates of these trace gases made from the Aura Tropospheric Emission Spectrometer (TES). The improvements are achieved by utilizing more of the inherent information available in the TES measurements. In previous versions of the TES profile retrieval algorithm, a "spectral-window" approach was used that attempted to minimize uncertainty from interfering specie. However, this approach can also reduce the vertical resolution of the retrieved species. Here we document the vertical sensitivity and error characteristics of retrievals in which H₂O, HDO, CH₄ and nitrous oxide (N₂O) are jointly estimated (together with temperature, surface emissivity, and cloud properties) using the spectral region between 1100 cm⁻¹ and 1330 cm⁻¹. The TES retrieval constraints are also modified to maximize the use of this information. The H₂O estimates show greater vertical resolution in the lower troposphere and boundary layer, while the new HDO/H₂O estimates can now profile the HDO/H₂O ratio between 925 hPa and 450 hPa in the tropics and during summertime at high latitudes. The new retrievals are now sensitive to methane in the free troposphere between 800 and 150 mb with peak sensitivity near 650 hPa. However, there is a bias in the upper troposphere of approximately 10 % that is likely related to temperature uncertainties and/or to errors in the methane spectroscopy. We discuss approaches for correcting this bias either through averaging or through correcting the estimated methane using co-estimated N₂O profiles. While these new CH₄, HDO/H₂O, and H₂O estimates are consistent with previous TES retrievals in the regions of overlap, future comparisons with independent profile measurement will be required to validate these new retrievals

[1] We present vertical distributions of ozone from the Tropospheric Emission Spectrometer (TES) over the tropical Atlantic Ocean during January 2005. Between 10N and 20S, TES ozone retrievals have Degrees of Freedom for signal (DOF) around 0.7 -0.8 each for tropospheric altitudes above and below 500 hPa. As a result, TES is able to capture for the first time from space a distribution characterized by two maxima: one in the lower troposphere north of the ITCZ and one in the middle and upper troposphere south of the ITCZ. We focus our analysis on the north tropical Atlantic Ocean, where most of previous satellite observations showed discrepancies with in-situ ozone observations and models. Trajectory analyses and a sensitivity study using the GEOS-Chem model confirm the influence of northern Africa biomass burning on the elevated ozone mixing ratios observed by TES over this region.

Abstract. We apply a continental-scale inverse modeling system for North America based on the GEOS-Chem model to optimize California methane emissions at 1/2° × 2/3° horizontal resolution using atmospheric observations from the CalNex aircraft campaign (May–June 2010) and from satellites. Inversion of the CalNex data yields a best estimate for total California methane emissions of 2.86 ± 0.21 Tg yr−1, compared with 1.92 Tg yr−1 in the EDGAR v4.2 emission inventory used as a priori and 1.51 Tg yr−1 in the California Air Resources Board (CARB) inventory used for state regulations of greenhouse gas emissions. These results are consistent with a previous Lagrangian inversion of the CalNex data. Our inversion provides 12 independent pieces of information to constrain the geographical distribution of emissions within California. Attribution to individual source types indicates dominant contributions to emissions from landfills/wastewater (1.1 Tg yr−1), livestock (0.87 Tg yr−1), and gas/oil (0.64 Tg yr−1). EDGAR v4.2 underestimates emissions from livestock while CARB underestimates emissions from landfills/wastewater and gas/oil. Current satellite observations from GOSAT can constrain methane emissions in the Los Angeles Basin but are too sparse to constrain emissions quantitatively elsewhere in California (they can still be qualitatively useful to diagnose inventory biases). Los Angeles Basin emissions derived from CalNex and GOSAT inversions are 0.42 ± 0.08 and 0.31 ± 0.08, respectively. An observation system simulation experiment (OSSE) shows that the future TROPOMI satellite instrument (2015 launch) will be able to constrain California methane emissions at a detail comparable to the CalNex aircraft campaign. Geostationary satellite observations offer even greater potential for constraining methane emissions in the future.